Hi. Thanks for looking at this question regarding a possible power steering ECU upgrade. Some background:
I purchased a 2003 LS430 last Oct (80k miles) with standard suspension. I have since upgraded the springs, struts and rear sway bar using OEM Euro/sport parts. It handles much better now, but the steering seems a bit over-boosted. I read that the power steering ECU for the Euro/sport susupension is different than the ECU for the standard suspension (a software remap?). That seems to be confirmed by the fact there are two different OEM part #s for the ECU (one original and one sport?). Here are the part numbers: 89650-50130 and 89650-50120.
The local, non-dealer repair shop that intalled the springs/struts/sway bar took apart the passenger side dash trying to find the power steering ECU, but no luck. Since then, I had a Lexus dealer tell me there is only one power steering ECU for all suspensions on 2003 LS430s. Can you confirm whether there were two different ECUs offered, and, if so, where the power steering ECU is located? (it's not behind the glove box, as part diagrams indicate.)
Any help/advice would be greatly appreciated.